US 7811702 B2
A microbattery has a support having a front face, a rear face, first and second current collectors arranged on the front face. A stack including a cathode and an anode separated by an electrolyte is arranged on the current collectors. The anode and cathode respectively contact the first and second current collectors. A protective layer covers the stack. The microbattery has connections in contact with the first and second current collectors, passing through the support from the front face to the rear face. The stack substantially covers of the front face of the support. A method for producing the mircobattery includes etching cavities, in the front face of the support, having a depth that is smaller than the thickness of the support, filing of the cavities with a conducting material and removing a layer of the rear face of the support to uncover the conducting material in the cavities.
1. Microbattery comprising
a support having a front face and a rear face,
first and second current collectors, arranged on the front face of the support,
a stack comprising an anode and a cathode separated by an electrolyte, the anode and cathode being in contact respectively with the first and second current collectors,
a protective layer covering the stack, and
electrical connection means in contact with the first and second current collectors and comprising connections that narrow as they pass through the support from the front face to the rear face thereof.
2. The microbattery according to
3. The microbattery according to
4. The microbattery according to
5. The microbattery according to
6. A method for producing the microbattery according to
etching, in the front face of the support, cavities having a depth that is smaller than the thickness of the support,
filling the cavities with a conducting material designed to constitute the connections that narrow as they pass through the support,
successively depositing, on the front face of the support, the first and second current collectors, of the stack and of the protective layer,
removing a layer of the rear face of the support so as to uncover the conducting material contained in the cavities.
7. The method according to
8. The method according to
9. The method according to
The invention relates to a microbattery comprising
As represented in
The energy stored in the battery depends essentially on the surface of the electrodes, i.e. of the anode 6 and cathode 8. Reducing the size of the batteries therefore requires the use of very thin layers to achieve the electrodes and the electrolyte. Moreover, when the microbattery is fitted on an integrated circuit chip, the available surface is often very limited.
Several microbatteries can be electrically associated in series or in parallel. In order to minimize the size of a device comprising a plurality of batteries, it is then sought to minimize the size of the contact pads.
Conventionally, fabrication of the batteries comprises coating processes of successive active layers constituting the anode, the electrolyte and the cathode. The anode, cathode and electrolyte being constituted by very reactive materials, the whole battery is usually covered by a protective or coating layer. Only the contact pads do not have to be covered, which is difficult to achieve, especially on a finished device.
One object of the invention is to remedy these shortcomings and in particular to minimize the size of a microbattery and to avoid a localized opening step of the contacts in the final phase of fabrication.
According to the invention, this object is achieved by the appended claims and more particularly by the fact that the electrical connection means comprise connections passing through the support from the front face to the rear face thereof.
It is a further object of the invention to provide a method for producing a microbattery according to the invention successively comprising:
Other advantages and features will become more clearly apparent from the following description of particular embodiments of the invention given as non-restrictive examples only and represented in the accompanying drawings, in which:
The microbattery represented in
In the particular embodiment represented in
As represented in
Successive deposition of the first 4 and second 5 current collectors, of the stack and of the protective layer 9, on the front face 2 of the support 1, is represented in
The anode 6 is for example achieved by thermal evaporation of lithium and it preferably, has a thickness comprised between 3 and 5 micrometers. The electrolyte 7 can contain a lithium compound such as lithium and phosphorus oxynitride, better known under the name of LiPON. The electrolyte 7 preferably has a thickness comprised between 1 and 2 micrometers. The current collectors 4 and 5 have for example a thickness comprised between 0.2 and 0.5 micrometers. The stack and the current collectors 4 and 5 can also be achieved by a Physical Vapor Deposition (PVD) method or by low-temperature vaporization.
Then, as represented in
The invention is not limited to the particular embodiment described above. In particular, the support 1 can be made of glass, ceramic (zircon, alumina) or polymer (polyether-ether-ketone PEEK; polyimide).